1. Field of the Invention:
The present invention is directed to thin walled poles to which external stores or loads are to be attached and to an apparatus for attaching these external stores to a thin walled pole.
2. Background of the Related Art:
It is sometimes desirable to use thin walled poles as load bearing members since they have high torsion and bending stiffness relative to their weight, as compared to solid poles. Often the thin walled poles are formed of a composite material such as a fiber reinforced plastic or resin material.
The attachment of external loads to such a thin walled pole presents particular problems. It is known to attach external loads via adhesives, particularly in the case of composite poles which cannot be welded. However, providing a secure adhesive attachment between the pole and external loads is labor intensive and lacks long term integrity for supporting the loads.
It would be desirable to be able to extend a bolt through the thin walled pole and tighten the bolt as a means for attaching external loads to the thin walled pole, much as such a bolt might be used for attachment of loads to solid poles. However, thin walled poles, particularly those formed of composite materials, have low resistance to local distortion and subsequent collapse due to radially compressive forces. Therefore, any attempt to tighten such a bolt onto the thin walled pole could easily result in local distortion and subsequent collapse of the thin walled pole.